Interjection

An interjection is a word at the beginning of a sentence of dialogue that expresses emotion.  It is set apart from the rest of the sentence by a comma (for weaker emotion)  or an exclamation point (for intense emotion).

• Wow!  That was amazing!
• Aw, I wanted to go outside, but it's raining.
• Golly gee, are you okay?

NOTE: An interjection is NOT a sentence!  An interjection is a word or phrase found at the beginning of a sentence.